Mail By Design: Keeping the USPS and Your Customers Happy

Quick printers who offer design services to their customers have a big task when asked to prepare something that will be mailed. If your quick print shop offers mailing services, then mail piece design is part of the technical expertise your customers have a right to expect from you. And if you don’t offer mailing services, then you need to know about mail piece design as a defense—to keep a mail house or the USPS from blaming you for extra postage requirements.

So what is a mail piece? For most quick printers, it is one of four things:

  • Postcard: A single ply, unfolded card. Depending on the size, postcards can be mailed first class using the subclass card, or they can be letter mail sent as first class presort or standard mail. Although postcards that are large enough may fall into the flat mail category, this is not common.
  • Self-mailer: A folded single sheet or unbound multiple sheets. A tri-fold brochure is a self-mailer; so is a four-page newsletter that prints 11x17" and folds down to 8.5x11" or 8.5x5.5". Self-mailers can be mailed as first class presort or standard mail in either the letter or flat category.
  • Booklet: Bound folded sheets, with or without a cover, such as an eight-page newsletter with two staples in the spine. As with a self-mailer, a booklet can be mailed as first class presort or standard mail in either the letter or flat category.
  • Envelope with enclosures: Depending on their size, envelopes can be letter mail (for example, a #10 or 6x9" envelope) or flat mail (for example, a 9x12" envelope). Envelopes can be mailed as first class presort or standard mail.

Mail Piece Design

When a printer says “design a mail piece,” we mean the artwork—the color palette, symmetry, perspective, graphic elements, typography—in other words, the aesthetics of the mail piece. When the USPS says “design a mail piece,” it means how efficiently it can be processed on high-speed equipment—the physical characteristics of the mail piece, the postage payment method, and whether the address includes machine readable postage coding.

The job of our graphic designers and CSRs is to understand the USPS requirements for card, letter, and flat mail and to either design to be compatible with them or explain to customers the postage implications of deviating from the requirements.

Determining Postage: Physical Characteristics

The physical characteristics of a mail piece are what determine the amount of postage required to mail it. Those characteristics are shape, size, thickness, weight, and flexibility. The shape that works best for USPS high speed mail processing equipment is a rectangle, and rectangular shape is determined by the aspect ratio (i.e.: the relationship of the long side to the short side, with the long side defined as the side parallel to the address). To compute the aspect ratio, divide the long side by the short side. If the answer falls between 1.3 and 2.5, then the mail piece is a rectangle. Other shapes can still be mailed, but at a higher postage rate.

Here is a tip about shape: A postcard that measures 4.25x5.5" (i.e.: one-quarter of an 8.5x11" sheet) has an aspect ratio of 1.29. If a bulk mail acceptance clerk allows rounding up, then the postcard meets the minimum requirement of 1.3. But without rounding, the postcard is not considered a rectangle. If, however, the postcard is trimmed to 4.125x5.5", then the aspect ratio is 1.33—within acceptable tolerance. Since we all have excellent cutters in our binderies, don’t try the patience of the bulk mail acceptance clerk. Be sure your graphic designer sets the size and trim marks for 4.125x5.5".

The USPS processes mail on two types of equipment: letter sorting and flat sorting. Letter sorting equipment runs at speeds up to 40,000 pieces per hour and is substantially faster than flat sorting equipment. So, just as the USPS prefers rectangular mail, it prefers letter mail. Here are the dimensions of letter mail and flat mail:

  • Letter mail is between 5" and 11.5" long, 3.5" to 6.125" high, 0.007" to 0.25" thick, and not more than 3.5 ounces in weight.
  • Flat mail is between 11.5" and 15" long, 6.125" and 12" high, 0.25" to 0.75" thick, and not more than 13 ounces in weight.
  • Card mail is a subcategory of letter mail with physical dimensions of between 5" and 6" long, 3.5" and 4.25" high, and 7 points to 0.25" thick. What your customers call a postcard could, depending on its size, be either a card or a letter. For example, a postcard measuring 4.25x6" is considered a card, while a postcard measuring 5.5x8.5" is considered letter mail.

Here is a tip about thickness: 7 point stock or a sheet of 20-pound bond that is trifolded will meet the minimum requirements. However, these are both so thin that the mail piece could arrive looking battered. Instead of meeting the minimum, select stock that is thick enough to travel well through the mail stream—at least 9 points for card stock and 60-pound offset for trifolds.

Determining Postage: The Address Panel

The address panel of a mail piece includes the return address, the indicia, and space for the outbound address and barcode. It also could include these optional elements: postal endorsements (tells the USPS what to do with mail that is undeliverable as addressed), teaser copy, and graphics.

The size of the address panel is important. It needs to be wide enough to comfortably contain the longest line in the outbound address, tall enough to comfortably contain the number of address lines (usually three or four, but sometimes more), as well as the postal coding lines (usually two) and barcode. At a minimum, make the address panel 2" high and 4.125" wide, but allow more room when possible.

For flat mail being mailed at the standard mail rate, locate the address panel in the upper half of the mail piece. This requirement applies both to envelopes and self-mailers, such as newsletters. It does not apply to flat mail being mailed at the first class presort rate, but to keep it simple, use the upper half of the mail piece for any flat.

For letter mail, locate the address panel 0.5" from the right edge and 0.625" (5/8") inch from the bottom of the mail piece. (The USPS designates the bottom 5/8" of the mail piece as a clear zone that must be free of all writing or graphics.) If you add the minimum dimensions of the address panel to the dimension from the right and bottom edges of the mail piece, then the minimum size for an address panel (measured from the right side and bottom edge of the mail piece) is 4.625" wide by 2.625" high.

Locate the indicia in the upper right corner and the return address in the upper left corner. Be sure that the last line of the return address is at least 2.75" from the bottom edge of the mail piece. Any lower and it will be in the MLOCR (multi-line optical character reader) clear area, which could result in the return address being confused with the outbound address and the mail mistakenly delivered back to the return address.

For a folded, unbound, letter size self-mailer, orient the address panel so the fold is at the bottom. Most self-mailers with a bottom fold require only one wafer seal (or tab).

Keep the area where the outbound address will appear clear of graphic design. Avoid any background or use a very faint screen. If the mail piece is a flood print, whether it is a solid ink color or a graphic element, knock out the area for the outbound address. The MLOCR requires good contrast between the background and the outbound address; insufficient contrast may render the mail piece not mailable at the best postage rates.

Here are two tips for the address panel: It does not have to be the entire face of an envelope or self-mailer, nor the entire right half of a postcard. It can have a landscape orientation (that is, parallel with the longest edge) to qualify as letter mail, even if the mail piece itself has a portrait orientation.

Recommending Paper and Coatings

When recommending the paper for a mail piece, make sure it is thick enough (at least 9 point), has sufficient flexibility to make the turns around the belts, rollers, conveyor wheels and drums of the USPS high speed mail processing equipment, and has sufficient opacity that printing on one side won’t show through to the address panel. Avoid stocks with patterns or dark fibers, fluorescent colors, and synthetic papers unless you know the mail house can address on synthetics (very few can).

Aqueous and UV coatings provide a special challenge for inkjet addressing—each requires a special ink formulary and a dryer to cure the ink. Before applying an aqueous or UV coating after printing, check to be sure the mail house can address on the coating.

Help From the USPS

The USPS offers much assistance for designing mail. Quick Service Guides summarize the requirements from the Domestic Mail Manual (DMM), two templates make it easy to determine aspect ratio and mail category (letter or flat), and a Mailpiece Design Analyst (MDA) is available to answer questions and determine the extent to which a mail piece meets design requirements.

Download PDFs of Quick Service Guide 201, 201b, 301, 301b, 602, 810, 811, and 820 from the Postal Explorer web site

Order Notice 67, Automation Template and Notice 3-A, Letter-size Mail Dimensional Standards Template from the business center that services your ZIP code or from your MDA. Find your MDA at

Train Your Staff

Train your CSRs to ask customers at job intake whether postage savings should be considered when designing the mail piece. If so, be sure the CSR conveys that information to the graphic designer. Train your graphic designer in the physical characteristics of mail pieces, address panel requirements, and the format for indicia.

Take these steps, and you’ll earn the best postage rates for your customers and the gratitude of the bulk mail acceptance clerk.

Nancy DeDiemar is the president of Printing Resources of Southern California, a quick print shop in Upland, CA, offering printing, copying, electronic prepress, and mailing services. Nancy is the co-publisher of Printips (, a newsletter subscription service for printers. Contact her at